E3 ubiquitin-protein ligase that promotes ubiquitination of DIO2, leading to its degradation. E3 ubiquitin ligases accept ubiquitin from an E2 ubiquitin-conjugating enzyme in the form of a thioester and then directly transfer the ubiquitin to targeted substrates. May cooperate with UBE2G1. {ECO:0000269|PubMed:15673284, ECO:0000269|PubMed:19651899}.